Chain grip pipe wrench



' March 12, 1957 Filed Nov. 9, 1954 0. s. MEREDITH 2,784,628

CHAIN GRIP PIPE WRENCH 2 SheetS -Sheet 1 INVENTOR ATTORNEY March 12, 1957 o. s. MEREDITH CHAIN GRIP PIPE WRENCH 2 Sheets-Sheet 2 Filed Nov. 9, 1954 @MRR R O T N E V m Q QKV/LLE 5: 449mm 71/ BY jam, all, 5

ATTORNEY United States Patent CHAIN GRIP PIPE WRENCH Orville S. Meredith, Skidmore, Tex. Application November 9, 1954, Serial No. 467,760

7 Claims. (CI. 81-68) This invention relates to wrenches, and in particular to a chain rgrip pipe wrench which automatically adjusts itself to the size of the pipe or other object upon which it must the gripped.

Conventional pipe wrenches such as Stillson or monkey- Wrenches suffer from two serious disadvantages. One is the manner in which they are tightened. A knurled nut .eifects the size adjustment for these wrenches. Frequently, the user needs to work with both hands and is all set to apply force to the Wrench when it becomes apparent that readjustment of the Wrench opening is needed. He must then set down his other tools and use both hands to adjust the wrench size through the knurled nut. Even more seriously, these conventional wrenches grip a pipeli'ke objectover a very small fraction of its circumferential area, e. g. '10 or 20%; frequently only four to eight of the serrations on the jaw faces of the wrench engage the pipe. As a result wrench marks are often left on the pipe. However, the most serious aspect of this characteristic lies in the great likelihood that the wrench will slip. Therein lies dangerous potentialities for injury to the wrench user. Slippage occurs most when the user is employing this full strength .on the wrench handle and at the same time is least poised for the sudden decrease of resistance occurring if the wrench slips. Falls and other accidental injuries result.

The prime object of this invention is to provide a self-adjusting pipe wrench. A second object of this invention is to provide a wrench wherein the gripping force of the jaws is commensurate to the pull exerted .on the wrench handle. Still another object of the invention is to provide a highly effective gripping mechanism on a wrench.

With these and other objects in View, the invention consists of a novel wrench construction, the principles of which are illustrated in the accompanying drawings and which is described in detail in the following specification,

wherein:

Figure 1 is a side elevational view of the wrench.

Figure 2 is a top view of a link chain forming part of the invention.

Figure 3 is a side View of the chain illustrated in Figure 2.

Figure 4 illustrates a serrated insert for a jaw.

Figure 5 is a side elevational view of the wrench handle and a sprocket gear.

Figure 6 is a side elevational view of the sprocket gear.

Figure 7 is a side elevational view of a jaw of the wrench.

Figure 8 is a fragmentary end view of the jaw looking toward the left in Figure 7.

Figure 9 is a side eleva-tional view of another jaw.

Figure 10 is an end view of the latter jaw.

Referring now to Figure 1 wherein is shown the assembled wrench 10, it can be seen that the wrench 10 comprises a slidable jaw 12, a stationary jaw 14, and an operating handle 16. The slidable jaw 12 (Figures 1 and 7) comprises a jaw face 18 having serrations 20 thereon. A grooved arm 22 is slidable along a suitable slot 24 on stationary jaw 14. The stationary jaw 14, as shown in Figures 9 and 10, has the slot 24 at its top. Somewhat below slot 24 is a pair of openings 26 for a roller 28. Roller 28 is rotatably mounted on pin 29. The latter can be secured on jaw 14 in any convenient manner as by peening the ends. As shown in Figure 1, grooved arm 22 of slidable jaw 12 is supported on and guided by the top of roller 28 as it slides along the slot 24. Stationary jaw 14 also has a set of openings 30. A serrated insert member 32 (Figure 4) which serves as the jaw face for stationary jaw 14 is attached to the stationary jaw by any suitable means such as pins disposed in openings 30.

In the assembled wrench, jaws 12 and 14 are urged to.- gether by the coaction of a link chain 34, a sprocket gear 36 and handle 16. One end of link chain 34 is secured to slidable jaw 12. A pair of longitudinal recesses 38 set in jaw face 18 just above serrations 20. The recesses 38 receive the end links and a fastening element, e. g. a pin or a rivet, passing through transverse opening 40 and the end links, secures the chain. The chain 34 eX- tends along the inner side of jaw 12 closely adjacent thereto, then passes under roller 28. The movable jaw 12 is thus guided along one side of the roller 28 and chain 34 is guided on the other side of roller 28 with the chain sliding over the roller as the wrench is operated. Sprockets 42 on gear 36 engage the links of chain 34 and when,"as hereinafter pointed out, leverage applied against handle 16 causes sprocket gear 36 to rotate, the chain 34 tightens up to draw jaws 12, 14 longitudinally together. A pipe or similar object A, set between the jaws 12, 14 becomes tightly gripped between the jaws. When the underside of chain 34 is provided with serrations 44 (Figure 3) the chain too acts as a gripping surface. If the jaw face 18 of slidable jaw 12 is curved as shown in the drawing, a full 80% of the circumferential surface of object A is encircled; of the circumferential surface can be actually contacted by the jaws and chain. As a result, a highly effective grip is accomplished, and large forces can be applied to turn object A Without slippage between wrench and pipe occurring. The scoring and damage which frequently results when conventional wrenches are used is thereby avoided.

To increase surface contact between object A and link chain 34, that end of the chain attached to slidable jaw 12 and normally in contact with object A may be made of rnultiple links as shown in Figure 2 with fine serrations 44 (Figure 3) at the bottom of each link. The rest of the chain may be made of unserrated standard links which are meshable with sprockets 42 on gear 36.

Sprocket gear 36 and handle 16 are structurally integrated as a unitary handle means so that pivoting or turning of handle 16 about its pivotal mount 46 causes rotation of gear 36. A preferred mode of eiiecting the integration is illustrated in the drawing (Figures 5, 6). Gear wheel 36 is eccentrically mounted on the same pin 46 which pivotally mounts handle 16. Suitable openings 48, 50, 52 provided respectively in stationary jaw 14, handle 16 and sprocket gear 36 receive pin 46. Handle 16 is bifurcated at its end sufliciently to receive therein sprocket gear 36 and link chain 34. In turn gear 36 and the bifurcated end of handle 16 are set inside stationary jaw 14. One (or each) face of gear 36 is provided with an integral lug 54 which matches cut-away section 56 on the bifurcated portion of handle 16. As a result, when leverage is applied to handle 16 and it tends to pivot on pin 46, lug 54 and the edges of cut-away section 56 coact to cause rotation of sprocket gear 36 in the same direction as the handle. Chain 34 which winds or un- Winds on gear 36, as the case may be, in turn forces slidable jaw 12 to move longitudinally towards or away from stationary jaw 14. The clamping pressure applied against object A is thus commensurate with the pull exented on handle 16.

Since it is not particularly desirable to leave free the part of link chain 34 which winds about sprocket gear 36, the end of link chain 34 may be secured to the gear itself. For this purpose a recess 58 is provided on sprocket gear 36 and the chain end attached therein, e. g. by a pin or rivet. While a form of the invention has been shown in detail, it has been done to illustrate the general principles involved and not for limiting the invention in any way as the scope of the invention is best defined in the accompanying claims.

I claim:

1. In a self-adjusting pipe wrench comprising a stationmy jaw, a slidable jaw, and a handle means pivotally connected to said stationary jaw, a flexible member secured at one end to said slidable jaw and at the other a suitable object for engagement therewith rotation of said handle causes said flexible member to move said slidable jaw toward said stationary jaw until upon engagement both said jaws and said flexible member are in gripping contact with said object.

2. In a self-adjusting pipe wrench comprising a serrated stationary jaw, a serrated slidable jaw and a handle pivotally mounted on said stationary jaw, a sprocket gear disposed on said handle at the pivotal mounting thereof for rotation around said mounting upon turning of said handle, a chain extending from a point of securement on said movable jaw, to a point of securement on said gear, whereby when the pipe wrench is positioned about a suitable object for engagement therewith rotation of said handle causes said chain to wrap around the gear and move said slidable jaw toward said stationary jaw until upon wrench engagement with said object both said jaws and a portion of said chain are in gripping contact with said object, the portion of said chain normally disposed between the jaws in an object gripping relationship being serrated.

3. A self-adjusting pipe wrench comprising a slidable jaw, a stationary jaw, a handle pivotally mounted in said stationary jaw, a sprocket gear mounted on said stationary jaw, means for interconnecting said sprocket gear and said handle to insure rotation of said gearupon turning of said handle, a link chain secured to said slidable jaw, said link chain extending along the inner side of said slidable jaw and engaged on the sprockets of said sprocket gear whereby when the pipe wrench is positioned about a suitable object for engagement therewith, rotation of said handle causes said chain to wrap around said gear and move said slidable jaw toward said stationary jaw until upon wrench engagement with said object both said jaws and a portion of said chain are in gripping contact with said jaws, the portion of said chain normally disposed between the jaws in object gripping relationship being serrated.

4. A self-adjusting pipe wrench comprising a stationary jaw, a handle pivotally mounted on said stationary jaw, a sprocket gear eccentrically mounted on said stationary jaw, means for interconnecting said sprocket gear and said handle to insure rotation of said gear upon turning of said handle, a slidable jaw, said slidable jaw sliding in a slot on said stationary jaw and along the top of a roller mounted on said stationary jaw, a link chain secured to said slidable jaw, said link chain extending along on the bottom of said roller and engaged on the sprockets of said sprocket gear whereby when the pipe Wrench is positioned about a suitable object for engagement therewith, rotation of said handle causes said chain to wrap around said gear and move said slidable jaw toward said stationary jaw until upon wrench engagement with said object both said jaws and a portion of said chain are in gripping contact with said jaws and a portion of said chain are in gripping contact with said object, the portion of said chain normally disposed between the jaws in object gripping relationship being serrated.

5. A pipe wrench as defined in claim 4 wherein the slidable jaw has a recess on the face thereof and said link chain is secured in said recess.

6. A pipe wrench as defined in claim 5 wherein the pivotal mounting of said handle serves also as the eccentric mounting for said sprocket gear.

7. A pipe wrench as defined in claim 6 wherein said handle has a bifurcated end portion, said sprocket gear being disposed in said bifurcated end portion, and wherein a lug on the face of said sprocket gear engaged in a recess on said bifurcated end portion serves as the means for interconnecting said sprocket gear and said handle.

References Cited in the file of this patent UNITED STATES PATENTS 

